Pigments are typically the more costly components of ink and toner. The cost of the conventional pigment dispersion process, in some instances, can reach as high as about 50% of the total cost of the pigment dispersion. Conventional pigment dispersion processes are very costly and energy intensive, which is time consuming and require frequent parts replacement and instrument maintenance.
The disclosure provides a cost effective process to prepare pigment dispersion by employing a method and system for magnetic actuated mixing which use magnetic particles and electromagnetic field to facilitate milling of different materials. In embodiments, the magnetic actuated mixing method can prepare ultrafine pigment dispersions having a pigment particle size of less than 100 nm.
It is known in the pigment art that the smaller the pigment particle size, the higher the color strength is produced. The color strength is an essential property of pigments. It defines the amount of pigment necessary to obtain a desired color shade. To reduce cost, the industry tends to achieve the most color strength from using the least possible amount of pigments. Thus, pigment loading can be reduced by using smaller particles pigment. Smaller pigment particles also provide better saturation, gloss, hiding power, dispersion, flow, and help prevent print head congestion. Thus, it is desirable to reduce the size of the pigment dispersions.
In the present embodiments, the mixing of materials uses the step of milling. Milling is the process of breaking down material and thus involves particle size reduction. The magnetic particles act as milling media. The system includes non-magnetic abrasive particles in the milling media to facilitate the milling. The present embodiments may be used in many different applications, including for example, preparing toners, inks, wax, pigment dispersions, paints, photoreceptor materials and the like. The present embodiments may be used for any application that requires the preparation of small-sized particles at either the micro or nano scale.
In many batch processes, the milling step is one of most critical steps to determine the overall performance of the process. For example, in applications where small-sized particles are produced, achieving the small scale and uniform distribution of the particles is determined by the milling step.